Using animal models, circulatory shock, acute and chronic hypoxia, and tissue ischemia will be studied. Whole body hemodynamics, organ function, and intracellular pO2, pCO2, pH, cation concentrations, and glucose will be correlated to cellular metabolic functions. Liver, kidney, and heart mitochondrial parameters will be measured in vivo and in vitro. The correlation of whole body, tissue, cellular, and subcellular parameters will be attempted, in hopes of uncovering the primary and secondary, possibly etiologic, factors involved in ischemic cellular and mitochondrial damage or in adaptation to altered environmental conditions. BIBLIOGRAPHIC REFERENCE: Tsou, K.C., Mela, L., Gupta, P.D., and Lymn, D.: Mitochondrial ultrastructure study with the new cytochrome c binding agent 4,4'-diamino-2,2'-bipyrodylferrous chelate. J. Ultrastr. Res. 54:235-242, 1976. Mela, L.: Mechanism and physiological significance of calcium transport across mammalian mitochondrial membranes. In Current Topics in Membranes and Transport (Bronner, F., and Kleinzeller, A., eds.). Academic Press, New York, in press 1977.